Cleaned up func removed unused variable (#29179)
Summary:
I don't see `_frames_up` being used anywhere. Just to clean up the code thought it should be removed.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/29179
Differential Revision: D18319876
Pulled By: suo
fbshipit-source-id: 5e612ff94ccc88fc85288ffc26213e1d11580c36
